Machine gun



March 19, i935. c, E, S IMPSON 1,994,489

MACHINE GUN" Filed April 20, 1954 II kmxav m v b awn/1111114111.?!)

6r... L u ///////////A MW/AS a 9 Attorney Inventur Patented Mar. 19, 1935 I 1 UNITED STATES PATENT OFFICE 1,994,489 I I I MACHINE GUN Clarence E. Simpson, Springfield, Mass.

Application April 20, 1934, Serial No. 721,564

2 Claims. (01. 42-75) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 75'!) The invention described herein may be manua barrel 7 slidably mounted in the trunnion block factured and used by or for the Government for and having a threaded connection 8 with a bargovernmental purposes, without the payment to rel extension 9 housed in the breech casing. An me of any royalty thereon. apertured jacket 10 which may be of any desired This invention relates to a machine gun. length, surrounds the barrel and is held in spaced 5 In a machine gun, head-space is the distance relation with respect thereto by virtue of its between the front face of the breech bolt and mounting which consists of a. threaded connecthe cartridge seating cone of the chamber of tion 11 on the trunnion block and a ring 12 fitthe gun barrel when these parts are in battery. ting on the barrel and preferably carried by the If the head-space is incorrect the gun will fail jacket. 10 to function or it will function unsatisfactorily, A portion of the barrel forward of the truncausing stoppages and damaging the parts. nion block is provided on its exterior surface In guns of the Browning type the barrel is with a plurality of longitudinally extending threadedly secured to the barrel extension and grooves 1313 adapted to selectively receive the 15 maintained in position relative thereto by a locktongue 14 of a latch 15. 5 ing spring carried by the barrel extension and The latch is in the form of a plunger and is selectively engageable in any one of a series of mounted in a cylinder 16 fixed to the jacket 10 notches on the barrel. The correct head space and projecting on the inside and the outside adjustment must be established by trial and this thereof. The outer end of the plunger is formed involves the tasks of assembling, disassembling, with a head 17 whereby it may be grasped and 20 adjusting and then reassembling the gun. withdrawn from engagement with the gun bar- With a view to permitting a more convenient rel. and more rapid adjustment for head-space the A helical spring 18, normally urging the plungpresent invention resides in the provision of an er towards the gun barrel, is confined between externally accessible latch for holding the barrel the closed inner end 19 of the plunger and a 25 in position of adjustment. plug 20 which is disposed in the plunger and With the foregoing and other objects in view, which is fixed to the cylinder 16 by a pin 21. the invention resides in the novel arrangement The pin 21 passes through bayonet slots 22--.-22 and combination of parts and in the details of in the opposite walls of the plunger. When the construction hereinafter described and claimed, plunger is depressed with its tongue 14 in one 0 it being understood that changes in the precise of the grooves 13 of the gun barrel Fig. 2, the embodiment of the invention herein disclosed pin 21 is at the outer or upper end of each slot may be made within the scope of what is claimed 22 (Fig. 2). When the plunger. is withdrawn without departing from the spirit of the invenfrom engagement with the barrel against the actiontion of the spring 18 (Fig. 4), it may be rotated 35 A practical embodiment of the invention is ilto place the pin in the inner offset portion of the lustrated in the accompanying drawing, wherein: bayonet slots, in which case the plunger is held Fig. 1 is a view partly in side elevation and in withdrawn position. partly in longitudinal section of a machine gun By virtue of this arrangement adjustment for 40 showing only the receiver, barrel and barrel head-space may be readily made without disas- 40 mountingsembling the gun. The operation consists mere- Fig. 2 is an enlarged longitudinal sectional view ly in withdrawing the plunger, rotating the barof the barrel lock. rel to advance or retract it relative to the barrel Fig. 3 is a sectional view on the line 33 of extension, determining the proper head-space Fig. 2. 'by trial of the gun'mechanism and then releas- 45 Fig. 4 is a sectional view showing the plunger ing the plunger. disengaged from the barrel. I claim: 7 V

Fig. 5 is a sectional View on the line 55 of 1. In a machine gun, a breech casing, a mem- Fig. 3. her within the casing, a barrel having one end Fig. 6 is a .view in elevation of the plunger. slidably mounted in the breech casing and 50 Referring to the drawing by characters of refthreadedly connected to said member, the outer erence, there is shown a portion of amachine gun portion of said barrel having an annularly arof the Browning air-cooled type, including a ranged series of longitudinally extending grooves, breech casing 4, a trunnion block 5 in the forward a jacket surrounding the barrel and attached to end of the casing, a breech bolt 6 in the casing, the barrel casing, a cylinder fixed in the jacket,

a plunger in the cylinder, said plunger having oppositely arranged bayonet slots, a plug within the plunger, 2. pin fixing the plug to the cylinder and passing through the bayonet slots of the plunger, and a spring confined between the plug and the plunger and normally holding the plunger in engagement with one of the grooves of the barrel. Y i

2. In a machine gun, a breech casing, a mem- 10 her within the casing, a barrel having one end slidably mounted in the breech casing and threadedly connected to said member, the outer portion of said barrel having an annularly arranged series of longitudinally extending grooves, a jacket surrounding the barrel and attached to the barrel casing, and a latch carried by the jacket and selectively engageable in the grooves ofthe barrel upon rotational displacement of the barrel.

, CLARENCE E. SIMPSON. 

